Can't set a custom backgroundColor with an if-query in applicationDidFinishLaunching

Question

Hello, my program normally has a standard background: "black.jpg". In the applicationDidFinishLaunching I did the following:

   [window addSubview:viewController.view];
   [window makeKeyAndVisible];
   viewController.view.backgroundColor = [UIColor colorWithPatternImage:[UIImage imageNamed:@"black.jpg"]];

and I have a nice black background. Now I want change my background and for this I made a preference. The defaultValue of the preference is 2, so why does the code not work?:

[window addSubview:viewController.view];        
[window makeKeyAndVisible];
NSUserDefaults *prefs = [NSUserDefaults standardUserDefaults];
int bla = [prefs stringForKey:@"background_key"];
NSlog(@"%@", bla) //Console says 2!!
        if (bla == 2) {
            viewController.view.backgroundColor = [UIColor colorWithPatternImage:[UIImage imageNamed:@"black.jpg"]];
        }

The view doesn't have the custom background. Thanks for your help!

Answer 1

1) Hmm, well the %@ qualifier throws me off ... I thought that is reserved for NS* objects. But if your getting 2, that's cool. I'd normally use %d as the qualifier though

2) int bla = [prefs stringForKey:@"background_key"]; Returns a string, not an int ...

3) Your comparison is probably hosed...

Answer 2

edit: see comments for the real reason :)

First use intValue

int bla = [[prefs stringForKey:@"background_key"] intValue];

and then compare.

Answer 3

A unique confluence of problems has confused you:

int bla = [prefs stringForKey:@"background_key"];

bla is now an int value, which holds the address of an NSString object.

NSlog(@"%@", bla) //Console says 2!!

As it should, since %@ says "take the object at the address I'm passing in, and ask for the description". Since the description of the string "2" is "2", you see "2"... If you wanted the format statement to correctly print an int you would need to use "%d", not "%@".

if (bla == 2) {
    viewController.view.backgroundColor = [UIColor colorWithPatternImage:[UIImage imageNamed:@"black.jpg"]];
}

But bla is not 2. It's something like 192322, because again it's holding the address of an object, not a pointer to the object.

If you really want an into to compare, use intValue on the result of the prefs call, as others have said. I just thought you might want to understand why the NSLog seemed to mislead you.